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Shifts in Arctic plants could accelerate warming

Pearson and colleagues (2013) recently showed how the expansion of shrubs and trees in the Arctic could promote even further warming through a series of positive feedbacks. Their modeling study that estimates the future composition and distribution of vegetation across the Arctic indicated shrubs and trees could expand by as much as 50% over current levels by 2050.

Shrubs and trees would replace more low-lying vegetation like grasses, sedges, and forbs. Whereas snow can easily cover low-lying vegetation, shrubs and trees are taller, and would be more exposed during the winter. Snow reflects solar radiation, but the darker color of exposed shrubs and trees would absorb more radiation, leading to increases in temperature. This so-called albedo effect is likely to speed up the pace of warming in the Arctic even further.

In a place where temperatures have risen twice as fast as other parts of the globe, additional feedbacks from vegetation in the Arctic would contribute to global warming. Further, as many animals rely on vegetation for food and habitat, a large shift in the type of vegetation is likely to lead to broader changes in the Arctic food web.

The photo is of Atigun Gorge, North Slope, Alaska. Photo credit: Jay Zarnetske.